Backlight device, display device with the same, and method of manufacturing the backlight device

ABSTRACT

According to one embodiment, a backlight device includes a frame formed of a sheet material, a first adhesive layer provided on one surface of the frame, a reflective sheet attached to the frame with the first adhesive layer, an optical member disposed on the reflective sheet in the frame, and a light source disposed in the frame and configured to emit light to the optical member. In at least a part of the frame, a width of the frame and a width of the first adhesive layer are equal to each other, and at least an external surface of the frame and an external surface of the first adhesive layer are flush with each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Applications No. 2015-225770, filed Nov. 18, 2015; andNo. 2016-115287, filed Jun. 9, 2016, the entire contents of all of whichare incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a backlight device, adisplay device with the same, and a method of manufacturing thebacklight device.

BACKGROUND

In recent years, liquid crystal display devices have come to be widelyused in smartphones, personal digital assistants (PDAs), tabletcomputers, satellite navigation systems, etc. In general, a liquidcrystal display device comprises a liquid crystal display panel and asurface illumination device (backlight device) which is overlaid on therear surface of the liquid crystal display panel and illuminates theliquid crystal display panel. An example of the surface illuminationdevice is a backlight unit including a reflective layer, a lightguideplate (lightguide), an optical sheet, LEDs as light sources, and arectangular mold frame. The reflective layer, the lightguide plate, andthe optical sheet are stacked on each other, and disposed in the moldframe. The peripheries of the reflective layer, the lightguide plate,and the optical sheet are thereby supported and positioned by the moldframe.

In recent years, as display areas have increased, there has been acontinual demand for the frames of liquid crystal display devices tobecome ever narrower and the liquid crystal display devices to becomeever thinner. However, the dimensions of the width, thickness, etc., ofthe mold frame in the above-described backlight unit is approaching thestructural limit of injection molding.

SUMMARY

The present application generally relates to a backlight device, adisplay device with the same, and a method of manufacturing thebacklight device.

In an embodiment, a backlight device is provided. The backlight deviceincludes a frame formed of a sheet material; a first adhesive layerprovided on one surface of the frame; a reflective sheet attached to theframe with the first adhesive layer; an optical member disposed on thereflective sheet in the frame; and a light source disposed in the frameand configured to emit light to the optical member, wherein in at leasta part of the frame, a width of the frame and a width of the firstadhesive layer are equal to each other, and at least an external surfaceof the frame and an external surface of the first adhesive layer areflush with each other.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a display surface side of a liquidcrystal display device according to a first embodiment.

FIG. 2 is a perspective view showing a rear surface side of the liquidcrystal display device.

FIG. 3 is an exploded perspective view of the liquid crystal displaydevice.

FIG. 4 is a sectional view of the liquid crystal display device takenalong line A-A of FIG. 1.

FIG. 5 is a sectional view of the liquid crystal display device takenalong line B-B of FIG. 1.

FIG. 6 is a diagram schematically showing an example of a manufacturingapparatus of backlight devices.

FIG. 7 is a perspective view showing a sheet material in manufacturingprocesses of the backlight devices.

FIG. 8 is a perspective view showing a state in which adhesive layersare formed on a first surface and a second surface of the sheetmaterial, respectively, in the manufacturing processes.

FIG. 9 is a perspective view showing a state in which inner windows(inner holes) of frames are punched in the manufacturing processes.

FIG. 10 is a perspective view showing a state in which a reflectivesheet is attached to one of the adhesive layers in the manufacturingprocesses.

FIG. 11 is a perspective view showing the backlight devices, the outershapes of which are formed by punching, in the manufacturing processes.

FIG. 12 is a diagram schematically showing another example of themanufacturing apparatus of the backlight devices.

FIG. 13 is a sectional view showing a part of the liquid crystal displaydevice comprising a backlight device manufactured by the manufacturingapparatus according to the above other example.

FIG. 14 is a sectional view showing a part of a liquid crystal displaydevice according to a second embodiment.

FIG. 15 is a perspective view showing a state in which adhesive layersare formed on a first surface and a second surface of a sheet material,respectively, in manufacturing processes of a backlight device accordingto the second embodiment.

FIG. 16 is a perspective view showing a state in which inner windows(inner holes) of frames are punched in the manufacturing processes.

FIG. 17 is a perspective view showing a state in which a reflectivesheet is attached to one of the adhesive layers in the manufacturingprocesses.

FIG. 18 is an exploded perspective view showing a stacked body in whichdepressions for accepting FPCs are formed and lightguide units in themanufacturing processes.

FIG. 19 is a perspective view showing a state in which the lightguideunits are mounted in the inner holes of the frames in the manufacturingprocesses.

FIG. 20 is a perspective view showing a state in which an optical sheetis attached to and overlaid on the frames and the lightguide units inthe manufacturing processes.

FIG. 21 is a perspective view showing a state in which adhesive layersare attached to the optical sheet in the manufacturing processes.

FIG. 22 is a perspective view showing the backlight devices, the outershapes of which are formed by punching in the manufacturing processes.

FIG. 23 is a sectional view showing a part of the liquid crystal displaydevice according to a first modification.

FIG. 24 is a perspective view showing an outside of the liquid crystaldisplay device according to a second modification.

FIG. 25 is a sectional view of the liquid crystal display device takenalong line C-C of FIG. 24.

DETAILED DESCRIPTION

Various embodiments will be described hereinafter with reference to theaccompanying drawings. In general, according to one embodiment, abacklight device comprises a frame formed of a sheet material; a firstadhesive layer provided on one surface of the frame; a reflective sheetattached to the frame with the first adhesive layer; an optical memberdisposed on the reflective sheet in the frame; and a light sourcedisposed in the frame and configured to emit light to the opticalmember. In at least a part of the frame, a width of the frame and awidth of the first adhesive layer are equal to each other, and at leastan external surface of the frame and an external surface of the firstadhesive layer are flush with each other.

The disclosure is merely an example, and proper changes within thespirit of the invention, which are easily conceivable by a person withordinary skill in the art, are included in the scope of the invention asa matter of course. In addition, in some cases, in order to make thedescription clearer, the widths, the thicknesses, the shapes, etc., ofthe respective parts are schematically illustrated in the drawings,compared to the actual modes. However, the schematic illustration ismerely an example, and adds no restrictions on the interpretation of thepresent invention. Further, in the specification and drawings, the sameelements as those described in connection with preceding drawings aregiven the same reference numbers, and a detailed description thereof isomitted as appropriate.

First Embodiment

FIG. 1 and FIG. 2 are perspective views showing a display surface sideand a rear surface side of a liquid crystal display device according toa first embodiment, respectively. FIG. 3 is an exploded perspective viewof the liquid crystal display device.

A liquid crystal display device 10 can be incorporated into variouselectronic apparatuses, for example, a smartphone, a tablet computer, afeature phone, a notebook computer, a portable game console, anelectronic dictionary, a television set, and a satellite navigationsystem.

As shown in FIG. 1 to FIG. 3, the liquid crystal display device 10comprises an active-matrix plate-shaped liquid crystal display panel 12,a transparent cover panel 14 overlaid on a display surface 12 a, whichis one flat surface of the liquid crystal display panel 12, and coveringthe whole display surface, and a backlight unit (backlight device) 20opposed to the rear surface side, which is the other flat surface of theliquid crystal display panel 12.

FIG. 4 is a sectional view of the liquid crystal display device takenalong line A-A of FIG. 1, and FIG. 5 is a sectional view of the liquidcrystal display device taken along line B-B of FIG. 1. As shown in FIG.3 to FIG. 5, the liquid crystal display panel 12 comprises a firstsubstrate SUB1 in the shape of a rectangular plate, a second substrateSUB2 in the shape of a rectangular plate opposed to the first substrateSUB1, and a liquid crystal layer LQ provided between the first substrateSUB1 and the second substrate SUB2. The periphery of the secondsubstrate SUB2 is affixed to the first substrate SUB1 with a sealingmember SE. A polarizer PL1 is attached to the surface of the firstsubstrate SUB1 to form the display surface 12 a of the liquid crystaldisplay panel 12. A polarizer PL2 is attached to the surface of thefirst substrate SUB1 (the rear surface of the liquid crystal displaypanel 12). In a sectional view taken along line A-A, the polarizer PL2has dimensions slightly greater than the outside dimensions of the firstsubstrate SUB1, and its end portion projects further outward than thatof the first substrate SUB1. In addition, in a sectional view takenalong line B-B, that end portion of the polarizer PL2, which is on theside opposite to light sources (described later), projects furtheroutward than the first substrate SUB1.

The liquid crystal display panel 12 is provided with a display area(active area) DA, which is rectangular in a planar view of the displaysurface 12 a, and an image is displayed in the display area DA. Inaddition, a frame area ED in the shape of a rectangular frame isprovided around the display area DA. The liquid crystal display panel 12is of a transmissive type which has a transmissive display function ofdisplaying an image by selectively transmitting light from the backlightunit 20 to the display area DA. As a display mode, the liquid crystaldisplay panel 12 may primarily include a structure corresponding to alateral electric field mode in which an electric field substantiallyparallel to a main surface of the substrate is used, or may primarilyinclude a structure corresponding to a vertical electric field mode inwhich an electric field substantially perpendicular to the main surfaceof the substrate is used.

In the shown example, a flexible printed circuit (FPC) 22 is joined toan end portion on a short side of the first substrate SUB1, and extendsoutward from the liquid crystal display panel 12. On the FPC 22, asemiconductor element such as a driving IC chip 21 is mounted as asignal supply source which supplies drive signals necessary to drive theliquid crystal display panel 12.

As shown in FIG. 1 to FIG. 5, the cover panel 14 is, for example, formedof a glass plate or an acrylic transparent resin and in the shape of arectangular plate. The cover panel 14 has greater dimensions (width andlength) than those of the liquid crystal display panel 12. Thus, thecover panel 14 has a larger area than that of the liquid crystal displaypanel 12 in a planar view. The lower surface (back surface) of the coverpanel 14, for example, is attached to the display surface 12 a of theliquid crystal display panel 12 with transparent adhesive AD, and coversthe whole display surface 12 a of the liquid crystal display panel 12.The periphery of the cover panel 14 projects further outward than theouter periphery of the liquid crystal display panel 12. Each of the longsides of the cover panel 14 is substantially parallel to the associatedlong side of the liquid crystal display panel 12, and is a predetermineddistance from the associated long side. Each of the short sides of thecover panel 14 is substantially parallel to the associated short side ofthe liquid crystal display panel 12, and is a predetermined distancefrom the associated short side. In the present embodiment, the distancebetween each long side of the cover panel 14 and each associated longside of the liquid crystal display panel 12, that is, the width of theperiphery on the long sides of the cover panel 14, is less than thedistance between each short side of the cover panel 14 and eachassociated short side of the liquid crystal display panel 12, that is,the width of the periphery on the short sides of the cover panel 14.

A light-shielding layer RS in the shape of a frame is formed on thelower surface (the back surface, or the surface on the liquid crystaldisplay panel side) of the cover panel 14. On the cover panel 14, anarea other than that opposed to the display area DA is shielded fromlight by the light-shielding layer RS. The light-shielding layer RS maybe formed on the upper surface (outer surface) of the cover panel 14.

As shown in FIGS. 3 to 5, the backlight unit 20 comprises a frame 16 inthe shape of a rectangular frame attached to the rear surface of theliquid crystal display panel 12, a reflective sheet RE attached to therear surface of the frame 16, optical members disposed in the frame 16,and a light source unit 30 which supplies light to be emitted to theoptical members.

The frame 16 is made of a sheet material having a thickness T1 of 0.40mm (400 μm) or less, for example, 0.15 to 0.25 mm (150 to 250 μm). Inaddition, the frame 16 is formed to have outside dimensions (width andlength) that are slightly greater than those of the liquid crystaldisplay panel 12 but less than those of the cover panel 14. As the sheetmaterial, a resin sheet, for example a sheet of polyethyleneterephthalate (PET), or a metal sheet, for example an aluminum sheet,can be used. The sheet material herein used includes a sheet having athickness of approximately 100 to 300 μm, a film or thin film having athickness less than 100 μm, etc.

As will be described later, the frame 16 is formed by punching the sheetmaterial, and has predetermined dimensions. The frame 16 is therebyformed to have the thickness T1 that is uniform over the wholeperimeter, and smooth in the thickness direction (z-direction insection). In the present embodiment, the thickness T1 of the frame 16(the thickness of the sheet material) is 0.188 mm (188 μm) or 0.25 mm(250 μm). It is preferable that the thickness T1 of the frame 16 (thethickness of the sheet material) be approximately 0.100 to 0.300 mm.

The frame 16 comprises a pair of longwise bars 16 a and 16 b opposed toeach other and a pair of sidelong bars 16 c and 16 d opposed to eachother. Each of the longwise bars 16 a and 16 b is formed to have a widthW1 of 0.6 mm (600 μm) or less, for example, 0.4 to 0.5 mm (400 to 500μm). The one sidelong bar 16 c is formed to have a width W2 of 0.6 mm(600 μm) or less, for example, 0.4 to 0.5 mm (400 to 500 μm), as in thecase of the width W1. In addition, the other sidelong bar 16 d may beformed to have a width W3 of 0.6 mm (600 μm) or less, for example, 0.4to 0.5 mm (400 to 500 μm), as in the case of the width W2. The width W3of the other sidelong bar 16 d may be greater than the width W2.Moreover, depressions 17 are provided on the inner side edge of theother sidelong bar 16 d.

A first adhesive layer 24 a is provided on the lower surface of theframe 16. In addition, a second adhesive layer 24 b is formed on theupper surface of the frame 16. For example, the first adhesive layer 24a has a thickness T2 of 0.03 to 0.06 mm (30 to 60 μm). The secondadhesive layer 24 b formed on the pair of ling-side portions 16 a and 16b and on the sidelong bar 16 c has a thickness T3 of 0.03 to 0.06 mm (30to 60 μm). Accordingly, except for the sidelong bar 16 d, the sum of thethicknesses of the frame 16, the first adhesive layer 24 a, and thesecond adhesive layer 24 b is, for example, 0.36 to 0.52 mm (360 to 520μm).

The first adhesive layer 24 a has a width equal to the width W1 of thelongwise bars 16 a and 16 b. At least the external surface of the frame16 and that of the first adhesive layer 24 a are flush with each other.In the present embodiment, the internal surface of the first adhesivelayer 24 a is also flush with that of the frame 16. In other words, interms of the distance between the longwise bars 16 a and 16 b of theframe 16, the inside dimension between the longwise bars 16 a and 16 band that of the first adhesive between on the longwise bar 16 a and onthe longwise bar 16 b are equal to each other. Similarly, the outsidedimension between the longwise bars 16 a and 16 b and that of the firstadhesive between on the longwise bar 16 a and on the longwise bar 16 bare equal to each other. That is, the longwise bars 16 a and 16 b andthe first adhesive layer 24 a formed thereon are not formed in such away that one of them is wider than the other, and their side surfacesare continuously aligned.

In the present embodiment, also at the sidelong bars 16 c and 16 d ofthe frame 16, the first adhesive layer 24 a has a width equal to thewidths W2 and W3 of the sidelong bars 16 c and 16 d. The external andinternal surfaces of the frame 16 are flush with those of the firstadhesive layer 24 a, respectively. In other words, in terms of thedistance between the sidelong bars 16 c and 16 d of the frame 16, theinside dimension between the sidelong bars 16 c and 16 d and that of thefirst adhesive layer 24 a between on the sidelong bar 16 c and on thesidelong bar 16 d are equal to each other. Similarly, the outsidedimension between the sidelong bars 16 c and 16 d and that of the firstadhesive layer 24 a between on the sidelong bar 16 c and on the sidelongbar 16 d are equal to each other.

As the first adhesive layer 24 a and the second adhesive layer 24 b,double-sided tape with adhesive layers on both surfaces of a basematerial is used in the present embodiment. These adhesive layers arethereby attached to the frame. The thickness of each of the adhesivelayers can be easily adjusted by changing the thickness of the basematerial. As the adhesive layers, for example, hotmelt adhesive, epoxyadhesive, and UV curing adhesive, can be used. If these kinds ofadhesive are used, the adhesive layers are formed by being applied tothe frame.

At least at the longwise bars 16 a and 16 b of the frame 16, the secondadhesive layer 24 b has a width equal to the width W1 of the longwisebars 16 a and 16 b. At least the external surface of the frame 16 andthat of the second adhesive layer 24 b are flush with each other. In thepresent embodiment, the internal surface of the second adhesive layer 24b is also flush with that of the frame 16. In other words, in terms ofthe distance between the longwise bars 16 a and 16 b of the frame 16,the inside dimension between the longwise bars 16 a and 16 b and that ofthe second adhesive layer 24 b between on the longwise bar 16 a and onthe longwise bar 16 b are equal to each other. Similarly, the outsidedimension between the longwise bars 16 a and 16 b and that of the secondadhesive layer 24 b between on the longwise bar 16 a and on the longwisebar 16 b are equal to each other.

In the present embodiment, also at the sidelong bars 16 c and 16 d ofthe frame 16, the second adhesive layer 24 b has a width equal to thewidths W2 and W3 of the sidelong bars 16 c and 16 d. The external andinternal surfaces of the frame 16 are flush with those of the secondadhesive layers 24 a, respectively. In other words, in terms of thedistance between the sidelong bars 16 c and 16 d, the inside dimensionbetween the sidelong bars 16 c and 16 d and that of the second adhesivelayer 24 b between on the sidelong bar 16 c and on the sidelong bar 16 dare equal to each other. Similarly, the outside dimension between thesidelong bars 16 c and 16 d and that of the second adhesive layer 24 bbetween on the sidelong bar 16 c and on the sidelong bar 16 d are equalto each other.

The second adhesive layer 24 b on the sidelong bar 16 c and each of thelongwise bars 16 a and 16 b of the frame 16 is formed thicker than thaton the sidelong bar 16 d on the light source side, and for example, isformed approximately twice thicker than that on the sidelong bar 16 d.In this case, two stacked adhesive layers each having a thickness equalto that of the first adhesive layer 24 a can be used as the secondadhesive layer 24 b. In addition, the second adhesive layer 24 b on thesidelong bar 16 d on the light source side is made thinner than that onthe longwise bars 16 a and 16 b, whereby a gap for passing a printedcircuit board 32 of the light source unit 30 is formed.

The reflective sheet RE is attached to the lower surface of the frame 16with the first adhesive layer 24 a, and covers the lower surface side ofthe frame 16. The reflective sheet RE is formed to have a film thicknessof 200 μm or less, and further, the film thickness is preferably 50 to90 μm. The reflective sheet RE has reflectivity of 90% or more, andfurther, the reflectivity is preferably 95% or more. In addition, thereflective sheet RE is formed into a rectangle having outside dimensionsequal to those of the frame 16. The external surface of the reflectivesheet RE is thereby flush with that of the frame 16. That is, each ofthe reflective sheet RE and the frame 16 does not project further thanthe other.

As shown in FIG. 3 to FIG. 5, the backlight unit 20 comprises opticalmembers stored in the frame 16. The optical members include a lightguideplate LG in the shape of a rectangle in a planar view and optical sheetsOS stacked on the lightguide plate LG. Moreover, the backlight unit 20comprises the light source unit 30 which is provided along one sidesurface (incidence surface) of the lightguide plate LG and which makeslight enter the lightguide plate LG.

The lightguide plate LG is formed by shaping transmissive resin into anextremely thin rectangle, and has the shape of like a rectangularparallelepiped. The lightguide plate LG comprises a first main surfaceS1 which is a light exit surface, a second main surface S2 on theopposite side to the first main surface S1, and an incidence surface EFconnecting the first main surface S1 and the second main surface S2. Inthe present embodiment, the incidence surface EF is one side surface onthe short sides of the lightguide plate LG. The lightguide plate LG hasdimensions (length and width) slightly less than the inside dimensionsof the frame 16 but slightly greater than the display area DA of theliquid crystal display panel 12. The thickness of the lightguide plateLG is the greatest on one side surface (incidence surface EF) sidefacing the light source unit 30, and is the smallest on the other sidesurface side on the opposite side to the one side surface. In thepresent embodiment, as the thickness of the lightguide plate LG, thethickness of the other side surface is, for example, approximately 0.2to 0.5 mm (200 to 500 μm).

The thickness T1 of the frame 16 is less than that of the thinnestportion of the lightguide plate LG. In addition, the sum of the platethickness of the lightguide plate LG and the thicknesses of the opticalsheets OS is substantially equal to that of the thickness T1 of theframe 16 and the thicknesses T2 and T3 of the first adhesive layer 24 aand the second adhesive layer 24 b. That is, the sum of the thicknessesof the lightguide plate LG and the optical sheets OS is, for example,0.36 to 0.52 mm (360 to 520 μm). Moreover, the extremely thin lightguideplate LG having a plate thickness of 0.02 mm (20 μm) or less also can beused. The lightguide plate LG is overlaid on the reflective sheet RE ina state in which the second main surface S2 is opposed to the reflectivesheet RE. The incidence surface EF is opposed to the sidelong bar 16 d.The other side surfaces of the lightguide plate LG are opposed to thesidelong bar 16 c and the longwise bars 16 a and 16 b with a small gapof approximately 0.05 to 0.2 mm (50 to 200 μm) therebetween,respectively.

The optical sheets OS have light transmitting properties, and aredisposed to be stacked on the first main surface S1 of the lightguideplate LG. In the present embodiment, a diffusion sheet OS1 and a prismsheet OS2 formed of synthetic resin, for example, polyethyleneterephthalate, are used as the optical sheets OS. The optical sheets OSare disposed to be stacked in order on the first main surface S1 of thelightguide plate LG. Each of the optical sheets OS is formed to have awidth equal to that of the lightguide plate LG and a length slightlyless than that of the lightguide plate LG, and formed to have dimensionsslightly greater than those of the display area DA. The side edgesexcept a side edge on the light source side, that is, three side edgesof each of the optical sheets OS are directly opposed to the frame 16with a predetermined gap (0.1 to 0.5 mm) therebetween. In addition, theoptical sheets OS are opposed to the rear surface of the liquid crystaldisplay panel 12 with a small gap therebetween. The optical sheets OSare thereby opposed to the whole display area DA.

As shown in FIG. 3 and FIG. 5, the light source unit 30 comprises theprinted circuit board (FPC) 32 in the shape of a narrow long strip, andlight sources mounted on the printed circuit board 32. As the lightsources, in the present embodiment, light-emitting diodes (LEDs) 34,which are point light sources, arranged at predetermined intervals areused. Each of the LEDs 34 comprises a light-emitting surface 34 a and amounting surface 34 b perpendicular to the light-emitting surface 34 a.The LEDs 34 are arranged at predetermined intervals in the longitudinaldirection of the printed circuit board 32 (direction parallel to thesidelong bars of the frame 16). Each of the LEDs 34 is mounted in astate in which the mounting surface 34 b is opposed to the printedcircuit board 32. In addition, the printed circuit board 32 comprises aconnection end portion 32 a extending from one side edge.

One longwise bar of the printed circuit board 32 is overlaid on thesidelong bar 16 d by the second adhesive layer 24 b, and the otherlongwise bar thereof is located on an end portion on the incidencesurface EF side of the lightguide plate LG. The LEDs 34 are therebydisposed between the sidelong bar 16 d and the incidence surface EF, andthe light-emitting surfaces 34 a are each opposed to the incidencesurface EF. In the present embodiment, the LEDs 34 are disposed in thedepressions 17 of the sidelong bar 16 d. For example, each of the LEDs34 preferably has a height (thickness) Lh of 0.4 mm (400 μm) or less,and more preferably has a height (thickness) Lh of 0.3 mm (300 μm) orless.

As the light sources, fluorescent tubes or cathode-ray tubes as linelight sources also can be adopted. Alternatively, as the light sources,line light sources or surface light sources obtained by disposingorganic electroluminescent light sources extremely closely can beadopted.

As shown in FIG. 5, a fourth adhesive layer, for example, double-sidedtape 37, is attached to an end portion on the light source side of theoptical sheet OS2 and to an end portion on the optical sheets side ofthe printed circuit board 32. In addition, one end portion on the lightsource side of the lowest optical sheet (diffusion sheet) OS1 extendsfurther to the light source side than that of the upper optical sheet(prism sheet) OS2, and is attached to the double-sided tape 37. Theoptical sheets OS1 and OS2 are thereby joined to the printed circuitboard 32 with the double-sided tape 37. In addition, since the printedcircuit board 32 is fixed to the frame 16, end portions on the mountingside of the optical sheets OS1 and OS2 are fixed to the frame 16 via theprinted circuit board 32.

Moreover, as shown in FIG. 3 and FIG. 5, a third adhesive layer in theshape of a narrow long strip, for example, double-sided tape 36, isoverlaid on and attached to the printed circuit board 32 and endportions of the optical sheets OS.

The backlight unit 20 having the above-described structure is disposedto be opposed to the rear surface of the liquid crystal display panel12, and attached to the polarizer PL2 with the second adhesive layer 24b and the double-sided tape 36.

That is, the pair of longwise bars 16 a and 16 b is attached to endportions on the long sides of the rear surface of the polarizer PL2 withthe second adhesive layer 24 b, respectively, and thereby locating alongthe long sides of the polarizer PL2. The sidelong bar 16 c is attachedto an end portion on a short side of the rear surface of the polarizerPL2 with the second adhesive layer 24 b, and located along the shortside of the polarizer PL2. The longwise bars 16 a and 16 b and thesidelong bar 16 c are thereby located to be overlaid on the frame areaED in a planar view, and are flush with a pair of long side surfaces anda short side surface of the polarizer PL2.

In the present embodiment, at the sides except the side on thelight-source mounting side, that is, at least three sides, the structurein which the end portion of the polarizer PL2 is flush with that of theliquid crystal display panel 12 or the structure in which the endportion of the polarizer PL2 is located further inward than that of theliquid crystal display panel 12 can be adopted.

The printed circuit board 32 attached to the other sidelong bar 16 d ofthe frame 16 is attached to, not the polarizer PL2, but the rear surfaceside of the first insulating substrate SUB1 of the liquid crystaldisplay panel 12 with the double-sided tape 36. The sidelong bar 16 d ofthe frame 16 and the light source unit 30 are thereby located to beoverlaid on the frame area ED of the liquid crystal display panel 12.

The optical sheets OS1 and OS2 and the lightguide plate LG are opposedto the display area DA of the liquid crystal display panel 12. Inaddition, the printed circuit board 32 of the light source unit 30 isconnected to the FPC 22 via the connection end portion 32 a (see FIG.2). A drive current is thereby supplied to the LEDs 34 via the FPC 22and the printed circuit board 32. Light emitted from the LEDs 34 entersthe lightguide plate LG from the incidence surface EF of the lightguideplate LG, and travels in the lightguide plate LG. The light exits fromthe second main surface S2 of the lightguide plate LG once, then isreflected by the reflective sheet RE, and enters the lightguide plate LGagain. After passing through such a light path, the light from the LEDs34 exits from the first main surface (light exit surface) S1 of thelightguide plate LG to the liquid crystal display panel 12 side. Theexiting light is diffused by the optical sheets OS, and then radiates tothe display area DA of the liquid crystal display panel 12.

Next, an example of a method of manufacturing the backlight unit(backlight device) 20 having the above-described structure will bedescribed. FIG. 6 is a diagram schematically showing an example of amanufacturing apparatus and all manufacturing processes. FIG. 7 to FIG.11 are perspective views schematically showing the state of a sheet inthe respective manufacturing processes.

As shown in FIG. 6, the manufacturing apparatus comprises rolls RP, RA1,RA2 a, RA2 b, RS1, RS2, and RR, each of which is formed by rolling along sheet like material, a pair of first conveyance rollers 80 a and 80b which conveys sheet materials drawn from the rolls along a conveyancepath CP, a pair of second conveyance rollers 82 a and 82 b, a collectionroll RC into which a separator is rolled and collected, a first punch P1and a second punch P2 which punch sheet materials moving along theconveyance path CP, etc.

The rolls include the roll RP, into which a sheet material for forming aframe, for example, a PET sheet 50, is rolled; the roll RA1, into whicha first adhesive layer is rolled; the rolls RA2 a and RA2 b, into whichsecond adhesive layers are rolled respectively; and the rolls RS1 andRS2, into which separators are rolled respectively. In the presentembodiment, only adhesive layers, or combinations of a base material andpressure-sensitive adhesive, are used as the first and second adhesivelayers. Double-sided tape may be used as the adhesive layers.

In addition, the width of each of the rolls is equal to the outsidedimension between the short sides of the backlight unit. Only the rollRA2 b has a width slightly less than those of the other rolls.

As shown in FIG. 6, first, sheet materials drawn from the rolls RP, RA1,RA2 a, RA2 b, RS1, and RS2, for example, the PET sheet 50, the firstadhesive layer 24 a, a second adhesive layer 24 b 1, a second adhesivelayer 24 b 2, and the separators, are conveyed through a space betweenthe pair of conveyance rollers 80 a and 80 b, and thereby stacked on andattached to each other. That is, as shown in FIG. 7 and FIG. 8, thefirst adhesive layer 24 a is attached to the whole lower surface (firstsurface) of the PET sheet 50. In addition, the second adhesive layer 24b 1 is attached to the whole upper surface (second surface) of the PETsheet 50, and further, the second adhesive layer 24 b 2 is attachedthereto in an area except a predetermined area along one side portion.Surfaces on the opposite side to those attached to the PET sheet 50 ofthe first adhesive layer 24 a and the second adhesive layer 24 b 2 arecovered by the separators.

Next, as shown in FIG. 6 and FIG. 9, the first adhesive layer 24 a, thesheet material 50, the second adhesive layers 24 b 1 and 24 b 2, and theseparators are punched together by the first punch (a metal mold, etc)P1, and rectangular inner holes 52 a and 52 b corresponding to the innershapes (inner holes) of frames are sequentially formed. Then, theseparator on the first adhesive layer 24 a is peeled off, and rolled andcollected into the collection roll RC. In this state, as shown in FIG. 6and FIG. 10, the reflective sheet RE drawn from the roll RR is attachedto the whole surface of the first adhesive layer 24 a. The sheetmaterial 50, the adhesive layers, and the reflective sheet RE passthrough a space between the pair of conveyance rollers 82 a and 82 b,and are conveyed along the conveyance path CP.

Then, as shown in FIG. 6 and FIG. 11, the first adhesive layer 24 a, thesheet material 50, the second adhesive layers 24 b 1 and 24 b 2, theseparator on the second adhesive layer 24 b 2, and the reflective sheetRE are punched together by the second punch (a metal mold, etc.) P2, andthe outer shapes of frames 16, reflective sheets RE, and first andsecond adhesive layers are formed at once. The frames 16 provided withthe reflective sheets RE and the adhesive layers are therebysequentially formed. Then, as shown in FIG. 6, backlight units 20 areobtained by mounting and fixing lightguide plates LG, optical sheets OS,and light source units 30 on the formed frames 16. The lightguide platesLG, the optical sheets OS, and the light source units 30 may be unitizedin advance by joining them to each other with adhesive layers, forexample, double-sided tape.

FIG. 12 schematically shows another example of the manufacturingapparatus and the manufacturing processes. In the present embodiment,double-sided tape is used as each of the first adhesive layer 24 a andthe second adhesive layer 24 b. The second adhesive layer 24 b has awidth slightly less than that of the first adhesive layer 24 a, and isprovided on the side portions except the sidelong bar 16 d. Namely, thesecond adhesive layer 24 b is provided on the pair of longwise bars 16 aand 16 b and the sidelong bar 16 c not on the light-source mountingside. The second adhesive layer 24 b is thicker than the first adhesivelayer 24 a, and for example, approximately twice thicker than the firstadhesive layer 24 a. The double-sided tape comprises a base material,adhesive layers formed on both surfaces of the base material, and aseparator attached to one of the adhesive layers. The double-sided tapeis rolled into the rolls RA1 and RA2. In addition, a loading device 84is provided between the pair of conveyance rollers 82 a and 82 b and thesecond punch P2.

According to the manufacturing processes in which the above-describedmanufacturing apparatus is used, as shown in FIG. 12, first, the PETsheet 50, the first adhesive layer (double-sided tape) 24 a, and thesecond adhesive layer (double-sided tape) 24 b drawn from the rolls RP,RA1, and RA2 are conveyed through the space between the pair ofconveyance rollers 80 a and 80 b, and thereby stacked on and attached toeach other. That is, the first adhesive layer 24 a is attached to thewhole lower surface (first surface) of the PET sheet 50, and the secondadhesive layer 24 b is attached to an area except a predetermined areaalong one side portion on the upper surface (second surface) of the PETsheet 50. The second adhesive layer 24 b is thereby formed on the frame.

Next, the first adhesive layer 24 a, the sheet material 50, and thesecond adhesive layer 24 b are punched together by the first punch (ametal mold, etc.) P1, and the rectangular inner holes 52 a and 52 bcorresponding to the inner shapes (inner holes) of the frames aresequentially formed. Then, the separator on the first adhesive layer 24a is peeled off, and rolled and collected into the collection roll RC.In this state, the reflective sheet RE drawn from the roll RR isattached to the whole surface of the first adhesive layer 24 a. Thesheet material 50, the first and second adhesive layers, and thereflective sheet RE pass through the space between the pair ofconveyance rollers 82 a and 82 b, and are conveyed along the conveyancepath CP.

Then, the lightguide plate LG, the optical sheets OS, and the lightsource unit 30 are mounted by the loading device 84 on predeterminedpositions of the sheet material 50 conveyed along the conveyance pathCP, which are herein the inner holes of the frames. After the mounting,the first adhesive layer 24 a, the sheet material 50, the secondadhesive layer 24 b, and the reflective sheet RE are punched together bythe second punch (a metal mold, etc.) P2, and the outer shapes of theframe 16, the reflective sheet RE, and the first and second adhesivelayers are formed at once. Backlight units 20 having predeterminedshapes are thereby sequentially produced.

FIG. 13 is a sectional view showing a part of the liquid crystal displaydevice comprising a backlight unit 20 manufactured by theabove-described other manufacturing apparatus. As shown in the figure, asecond adhesive layer does not exist on the sidelong bar 16 d on thelight source side of the frame 16. A gap through which the printedcircuit board 32 passes is thereby secured between the sidelong bar 16 dand the first insulating substrate SUB1.

According to the liquid crystal display device 10, the backlight device,and the method of manufacturing the backlight device according to thepresent embodiment having the above-described structure, a frame of abacklight is formed by punching a thin sheet having a thickness of 0.4mm (400 μm) or less, for example, a thickness of 0.15 to 0.25 mm (150 to250 μm). A thin frame with narrow side portions, which is hard toproduce by injection molding, can be thereby obtained. By using theframe, a backlight device and a liquid crystal display device which areever thinner and have narrow frames can be achieved at low prices. Forexample, the thickness of a frame can be 0.2 mm or less, and the widthof side portions can be 0.45 mm or less. A reduction in thickness andthe narrowing of the frame can be easily achieved. Moreover, since theframe is made thinner, an extremely thin lightguide plate having a platethickness of 0.2 mm or less can be used. Thus, an ever thinner backlightdevice can be obtained.

In addition, since a sheet, an adhesive layer formed on or attached tothe sheet, and a reflective sheet are punched at once together with theframe, the width of the adhesive layer and the outside dimensions of thereflective sheet can be conformed to the frame at high precision.

In contrast to the present embodiment, in a comparative example in whichadhesive layers are attached or applied to a frame afterward, it is hardto provide adhesive layers on the upper and lower surfaces of the framein conformity to the width of the frame because the width of the frameis extremely small, and the adhesive layers will project. The projectingadhesive not only has a bad influence on subsequent processes, but alsocauses a decrease in the light-emitting performance of a backlightdevice if it adheres to the other structures of the backlight device. Incontrast, in the backlight device of the present embodiment, theadhesive layers do not project. Thus, the width of the adhesive layersis conformed to that of the side portions of the frame, and the sidesurfaces (side edges) of the adhesive layers and those of the frame areflush with each other. Since an increase in the width of the frame dueto the projection of the adhesive layers is suppressed, and a reductionin thickness and the narrowing of the frame are attempted. Moreover,since the sheet, the adhesive layers, and the reflective sheet arepunched at once, the simplification of manufacturing processes and animprovement in the precision of each member are attempted. In addition,the tolerance between each member, which is required when the membersare separately formed and stacked, can be reduced, and a furtherreduction in thickness and the further narrowing of the frame areattempted. Moreover, according to the present embodiment, it isunnecessary to attach or manage the adhesive layers in the manufacturingprocesses of the backlight device, and the simplification of themanufacturing processes and a reduction in the manufacturing cost can beattempted.

If a frame is formed of a resin sheet, colors other than white, forexample, gray and black, can be adopted as the colors of the frame andadhesive layers. Thus, light reflected in the internal surface of theframe can be reduced, and the inside of the frame can be made evercloser to the display area of the display panel. Moreover, thehomogeneity of light emitted to the whole display area including theperiphery of the display area can be improved. In addition, if a frameis formed of a metal sheet of aluminum, etc., the heat radiationproperty of the frame is improved, and an increase in the temperature ofa backlight device caused by the emission of light from a light sourcecan be suppressed.

Next, a liquid crystal display device according to another embodimentwill be described. In the other embodiment described hereinafter, thesame portions as those of the above-described first embodiment will begiven the same reference numbers and a detailed description thereof willbe omitted or simplified. Portions differing from those of the firstembodiment will mainly described in detail.

Second Embodiment

FIG. 14 is a sectional view showing a part of a liquid crystal displaydevice according to a second embodiment.

As shown in FIG. 14, according to the liquid crystal display device ofthe present embodiment, for example, the highest optical sheet (prismsheet) OS2 stacked on a lightguide plate LG is formed to have dimensionsgreater than those of the lightguide plate LG and the other opticalsheet OS1. At least three side portions of the optical sheet OS2, exceptfor a side portion on the light source unit side, cover a gap betweenthe lightguide plate LG and a frame 16. In the present embodiment, thethree side portions of the optical sheet OS2 extend outward to positionscorresponding to the external surface of the frame 16. The periphery ofthe optical sheet OS2 is attached to the upper surface of the frame 16with a second adhesive layer 24 b. Moreover, a fifth adhesive layer 24 cin the shape of a strip is provided on the upper surface of theperiphery of the optical sheet OS2. The fifth adhesive layer 24 cconstitutes an adhesive layer for attaching a backlight unit 20 to adisplay panel 12.

At at least three side portions of the frame 16, except for a sideportion on the light source unit side, the external surface of the frame16, the external surface of a first adhesive layer 24 a, the externalsurface of the second adhesive layer 24 b, the external surface of thesecond optical sheet OS2, and the external surface of the fifth adhesivelayer 24 c are flush with each other. In the present embodiment, theinternal surface of the first adhesive layer 24 a, the internal surfaceof the second adhesive layer 24 b, and the internal surface of the fifthadhesive layer 24 c are also flush with the internal surface of theframe 16. The structure in which the internal surface of the fifthadhesive layer 24 c does not correspond to the internal surfaces of theother adhesive layers and the frame also can be adopted.

As the fifth adhesive layer 24 c, double-sided tape with adhesive layerson both surfaces of a base material is used in the present embodiment.The thickness of each of the adhesive layers can be easily adjusted bychanging the thickness of the base material. As the adhesive layers, forexample, hotmelt adhesive, epoxy adhesive, and UV curing adhesive, canbe used. The other structures of the backlight unit 20 are the same asthose of the backlight unit in the above-described first embodiment.

The backlight unit 20 having the above-described structure is attachedto a polarizer PL2 of the liquid crystal display panel 12 with the fifthadhesive layer 24 c and double-sided tape not shown in the figure.

Next, an example of a method of manufacturing the backlight unit(backlight device) 20 having the above-described structure will bedescribed. In the present embodiment, the backlight unit 20 ismanufactured by using substantially the same manufacturing apparatus asthe manufacturing apparatus shown in FIG. 12. Double-sided tape is usedas each of the first adhesive layer and the second adhesive layer. Thedouble-sided tape comprises a base material, adhesive layers formed onboth surfaces of the base material, and a separator attached to one ofthe adhesive layers. The double-sided tape is rolled into rolls RA1 andRA2. In addition, a loading device 84 is provided between a pair ofconveyance rollers 82 a and 82 b and a second punch P2.

First, a PET sheet 50, the first adhesive layer (double-sided tape) 24a, and the second adhesive layer (double-sided tape) 24 b drawn from aroll RP, the roll RA1, and the roll RA2 are conveyed through a spacebetween a pair of conveyance rollers 80 a and 80 b, and thereby stackedon and attached to each other. That is, as shown in FIG. 15, the firstadhesive layer 24 a is attached to the whole lower surface (firstsurface) of the PET sheet 50, and the second adhesive layer 24 b isattached to the whole upper surface (second surface) of the PET sheet50. In FIG. 15 and subsequent figures, arrows indicate the conveyancedirections of a sheet, double-sided tape, etc., drawn from rolls.

Next, as shown in FIG. 16, the first adhesive layer 24 a, the sheetmaterial 50, and the second adhesive layer 24 b are punched together bya first punch (a metal mold, etc.) P1, and rectangular inner holes 52 a,52 b, and 52 c corresponding to the inner shapes (inner holes) of framesare sequentially formed. Then, a separator on the first adhesive layer24 a is peeled off, and rolled and collected into a collection roll RC.Moreover, a reflective sheet RE drawn from a roll RR, the sheet material50, and the first and second adhesive layers pass through a spacebetween the pair of conveyance rollers 82 a and 82 b, and are conveyedalong a conveyance path CP. As shown in FIG. 17, a stacked body with thereflective sheet RE attached to the whole surface of the first adhesivelayer 24 a is thereby formed.

As shown in FIG. 18, depressions 88 for accepting FPCs of light sourceunits 30 are formed at a side edge of the stacked body by a punch notshown in the figure. In addition, lightguide units 90, into whichlightguide plates LG, optical sheets OS1, and the light source units 30are assembled, are prepared. As shown in FIG. 19, the lightguide units90 are sequentially mounted by the loading device 84 on predeterminedpositions of the sheet material 50 conveyed along the conveyance pathCP, which are herein the inner holes 52 a, 52 b, and 52 c of the frames.In a state in which the lightguides LG and the optical sheets OS1 aremounted in the inner holes 52 a, 52 b, and 52 c, the upper surfaces ofthe optical sheets OS1 are flush with the second adhesive layer 24 b offrames 16.

Next, as shown in FIG. 20, the optical sheet (prism sheet) OS2 is drawnfrom a roll not shown in the figure, and stacked on and attached to thesecond adhesive layer 24 b of the stacked body. The optical sheet OS2covers the frames 16 and the optical sheets OS1 except the light sourceunits 30. Then, as shown in FIG. 21, the fifth adhesive layer(double-sided tape) 24 c is drawn from a roll not shown in the figure,and stacked on and attached to the optical sheet OS2 and the lightsource units 30 of the stacked body. Inner holes 92 a, 92 b, and 92 care formed in advance in the fifth adhesive layer 24 c. Then, the fifthadhesive layer 24 c is attached to the optical sheet OS2 in a state inwhich the inner holes 92 a, 92 b, and 92 c are aligned with the innerholes 52 a, 52 b, and 52 c of the sheet material 50, respectively.

After the fifth adhesive layer 24 c is attached, the fifth adhesivelayer 24 c, the optical sheet OS2, the first adhesive layer 24 a, thesheet material 50, the second adhesive layer 24 b, and the reflectivesheet RE are punched together by the second punch (a metal mold, etc.)P2. As shown in FIG. 22, the outer shapes of the frames 16, reflectivesheets RE, optical sheets OS2, and first, second, and fifth adhesivelayers 24 a, 24 b, and 24 c are thereby formed at once. At this time,punching can be performed without damaging the FPCs by punching the endportion on the light source side of the stacked body in a state in whichFPCs (connection end portions) 32 a of the light source units 30 areretracted into the depressions 88 of the stacked body. Backlight units20 having predetermined shapes are thereby sequentially produced.

According to the above-described second embodiment, a backlight deviceand a liquid crystal display device which are thin and have narrowframes can be achieved at low cost as in the case of the firstembodiment. In addition, a gap between the lightguide plate LG and theframe 16 is covered by the optical sheets OS. Thus, light in thevicinity of the frame 16 of light emitted from the lightguide plate LGalso passes through the optical sheets OS. As a result, even if thedisplay surface of the liquid crystal display panel 12 is visuallyperceived, non-uniformity in brightness at the periphery of thelightguide plate LG is sufficiently suppressed, and an improvement indisplay quality is attempted. Moreover, if the frame 16 and adhesivelayers 24 a, 24 b are colored not white (for example, black),unnecessary light due to the reflection in the internal surface of theframe 16 can be reduced, and the brightness state of the inner surfaceside of the frame 16 can be made closer to that of the central portionof the display area DA. As a result, a backlight device wherein thefurther narrowing of the frame can be attempted can be achieved.

(First Modification)

FIG. 23 is a sectional view showing a part of the liquid crystal displaydevice according to a first modification of the liquid crystal displaydevice of the second embodiment.

As shown in the figure, for example, the highest optical sheet (prismsheet) OS2 stacked on the lightguide plate LG is formed to havedimensions greater than those of the lightguide plate LG and the otheroptical sheet OS1. At least the pair of longwise bars and the sidelongbar on the opposite side to the light source unit of the optical sheetOS2 cover a gap between the lightguide plate LG and the frame 16.According to the liquid crystal display device according to the presentmodification, the pair of longwise bars and the sidelong bar on theopposite side to the light source unit of the optical sheet OS2 arelocated further inward than the external surface of the frame 16. Theperiphery of the optical sheet OS2 is attached to the upper surface ofthe frame 16 with the second adhesive layer 24 b. Moreover, the fifthadhesive layer 24 c in the shape of a strip is provided on the uppersurface of the periphery of the optical sheet OS2.

At at least the longwise bars 16 a and 16 b and the sidelong bar 16 c,the external surface of the second optical sheet OS2, and that of thefifth adhesive layer 24 c are flush with each other. In the presentmodification, the internal surface of the fifth adhesive layer 24 c isalso flush with that of the frame 16. Moreover, a resin adhesive layer94 having a light-shielding property covers the external surface of thesecond optical sheet OS2 and the external surface of the liquid crystaldisplay panel 12. Light leakage from the external surfaces of the secondoptical sheet OS2 and the liquid crystal display panel 12 can be therebysuppressed.

The other structures of the backlight unit 20 are the same as those ofthe backlight unit in the above-described second embodiment.

In the first modification having the above-described structure, inaddition to the advantages of the second embodiment, light leakage fromthe external surfaces of the second optical sheet OS2 and the liquidcrystal display panel 12 can be further prevented. As a result, alight-shielding function on the apparatus side of a display device,which is incorporated into the apparatus, can be simplified.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

All of the structures and manufacturing processes that can beimplemented by a person with ordinary skill in the art through arbitrarydesign changes based on the structures and manufacturing processesdescribed above as the embodiments of the present invention are includedin the scope of the present invention as long as they encompass thespirit of the present invention.

Furthermore, other advantages that can be obtained by theabove-described embodiments and are obvious from the description of thisspecification or can be conceived by a person with ordinary skill in theart as appropriate are naturally acknowledged as advantages of thepresent invention.

The number of optical sheets of the backlight unit is not limited totwo, and may be increased or reduced as necessary. The outer and innershapes of the liquid crystal display panel, the components of thebacklight unit, and the frame are not limited to rectangles. Either orboth of them may be other shapes such as circles, ellipses, and trackshapes. Alternatively, they may be shapes with one or more curved sides.Materials used for the components are not limited to the above-describedexamples and may be selected from various options.

Moreover, each of the backlight devices of the present embodiments isextremely thin, and thus can easily curved as a whole in an out-of-planedirection. For example, as in the case of a second modification shown inFIG. 24 and FIG. 25, the structure of the liquid crystal display devicein which the backlight unit 20 is attached to the liquid crystal displaypanel 12 and they are curved together in this state also can be adopted.

What is claimed is:
 1. A backlight device comprising: a frame formed ofa sheet material; a first adhesive layer provided on one surface of theframe; a reflective sheet attached to the frame with the first adhesivelayer; an optical member disposed on the reflective sheet in the frame;and a light source disposed in the frame and configured to emit light tothe optical member, wherein in at least a part of the frame, a width ofthe frame and a width of the first adhesive layer are equal to eachother, and at least an external surface of the frame and an externalsurface of the first adhesive layer are flush with each other.
 2. Thebacklight device of claim 1, wherein an external surface of thereflective sheet is flush with the external surfaces of the firstadhesive layer and the frame.
 3. The backlight device of claim 1,wherein the frame has a thickness of 0.4 mm or less.
 4. The backlightdevice of claim 1, wherein the frame has a uniform thickness over awhole perimeter.
 5. The backlight device of claim 1, wherein the framecomprises bars, and in at least one of the bars, the width of the frameis 0.6 mm or less.
 6. The backlight device of claim 5, wherein a widthof each of the bars and the width of the first adhesive layer are equalto each other, and an external surface and an internal surface of thebar are flush with the external surface and an internal surface of thefirst adhesive layer, respectively.
 7. The backlight device of claim 1,further comprising a second adhesive layer provided on an other surfaceopposed to the one surface, wherein, in at least a part of the frame,the width of the frame and a width of the second adhesive layer areequal to each other, and the external surface of the frame and anexternal surface of the second adhesive layer are flush with each other.8. The backlight device of claim 1, wherein the frame comprises at leastfour side portions, a second adhesive layer is provided on an othersurface opposed to the one surface, and in three successive sideportions of the frame, the width of the frame and a width of the secondadhesive layer are equal to each other, and the external surface and aninternal surface of the frame are flush with an external surface and aninternal surface of the second adhesive layer, respectively.
 9. Thebacklight device of claim 8, wherein the optical member includes alightguide plate provided on the reflective sheet and an optical sheetdisposed on the lightguide plate, and each of a sum of thicknesses ofthe lightguide plate and the optical sheet and a sum of thicknesses ofthe frame, the first adhesive layer, and the second adhesive layer is0.36 to 0.52 mm.
 10. The backlight device of claim 9, wherein theoptical sheet comprises a peripheral portion covering a gap between thelightguide plate and the frame, and the peripheral portion is attachedto the frame with the second adhesive layer.
 11. The backlight device ofclaim 10, wherein, the frame includes bars, the external surface of theone of the bars and an external surface of the optical sheet are flushwith each other.
 12. The backlight device of claim 11, wherein alight-shielding resin layer covering the external surface of the opticalsheet is provided.
 13. The backlight device of claim 1, wherein thesheet material is one of a resin sheet and a metal sheet.
 14. A displaydevice comprising: a liquid crystal display panel; and the backlightdevice of claim 1, the backlight device being opposed to the liquidcrystal display panel.
 15. The display device of claim 14, wherein theframe of the backlight device is attached to the liquid crystal displaypanel with a second adhesive layer.